U.S. Pat. Nos. 7,564,150 and 7,642,673 disclose operator control apparatuses in which an operator control element, which can move freely per se, can be mounted on a mounting point on an operator control surface of an electric hob for rotary operation. If the operator control element is mounted on the mounting point, an associated cooking point of the electric hob can be adjusted, for example in terms of power. If the operator control element is removed, the functional state of the cooking point cannot be changed.